Research has been constructed for the past 200 years. The production Origin of Lead in Eight Central of Ag-Pb, coal, and leaded gasoline peaked in 1900, European Peat Bogs Determined 1980, and 1980, respectively. In contrast to other European countries, no peak in annual Pb accumulation rates was from Isotope Ratios, Strengths, and found in 1900, the year of maximum ore smelting. The highest Operation Times of Regional annual Pb accumulation rates in peat were consistent with the highest Pb emission rates from coal-fired power Pollution Sources plants and traffic (1980). Although maximum coal and gasoline production coincided in time, their isotope ratios 206 207 MARTIN NOVAÄ K,*,² SIMON EMMANUEL,³ were unique. The mean measured Pb/ Pb ratios of MELANIE A. VILE,§ YIGAL EREL,³ local coal, ores, and gasoline were 1.19, 1.16, and 1.11, ALAIN VEÄ RON,| TOMAÄ Sˇ PACˇ ES,² respectively. A considerable proportion of coal emissions, ⊥ R. KELMAN WIEDER, MIRKO VANEˇ Cˇ EK,# relative to gasoline emisions, was responsible for the MARKEÄ TA Sˇ TEˇ PAÄ NOVAÄ , ² 206 207 ˇ Ä Ä O ∇ higher Pb/ Pb ratios in the recent atmosphere (1.15) EVA BRI ZOVA, AND JAN HOVORKA compared to Western Europe (1.10). As in West European Department of Geochemistry, Czech Geological Survey, countries, the gasoline sold in the Czech Republic Geologicka 6, 152 00 Prague 5, Czech Republic, - Institute of Earth Sciences, The Hebrew University, during the Communist era (1948 1989) contained an Jerusalem 91904, Israel, Department of Ecology and admixture of low-radiogenic Precambrian lead from Australia. Evolutionary Biology, 106A Guyot Hall, Princeton University, Princeton, New Jersey, CEREGE, UMR CNRS 6635, Universite Aix-Marseille, Europole Mediterraneen, BP80 Plateau Petit Introduction Arbois, 13545 Aix en Provence, France, Department of Biology, Villanova University, Villanova, Pennsylvania 19085, More lead has been released into the environment since Geofond of the Czech Republic, Kostelnõ 26, 170 21 Prague 7, prehistory than any other metal (1). As late as 1990, 50% of Czech Republic, Department of Quaternary Research, the annual worldwide Pb production was still being lost to Czech Geological Survey, KlaÂrov 3, 118 21 Prague 1, the atmosphere (2). Direct data concerning atmospheric Pb Czech Republic, and Institute for Environmental deposition rates cover only the past 30 years; data prior to Studies, Charles University, BenaÂtskaÂ2, this period must be reconstructed indirectly from geochemi- 128 01 Prague 2, Czech Republic cal records (3). Anthropogenic lead is mostly adsorbed on particles and scattered by aeolian transport, with sediments representing the ultimate sinks for Pb emissions. Om- brotrophic peat deposits have been used as relatively high- Lead originating from coal burning, gasoline burning, and resolution archives of Pb pollution levels for the past 12 000 210 ore smelting was identified in Pb-dated profiles through years, i.e., throughout the Holocene Epoch (4). In Europe, eight peat bogs distributed over an area of 60 000 km2. vertical peat profiles have been most extensively studied in The Sphagnum-dominated bogs were located mainly in three countries: U.K. (5), Sweden (6), and Switzerland (3, 4). mountainous regions of the Czech Republic bordering with Here, we report on the origin of lead in eight 210Pb-dated Germany, Austria, and Poland. Basal peat 14C-dated at peat cores from blanket bogs situated in Central Europe, 11 000 years BP had a relatively high 206Pb/207Pb ratio (1.193). mainly in the mountaineous border regions of the Czech Peat deposited around 1800 AD had a lower 206Pb/207Pb Republic. This area is known for its long history of silver and ratio of 1.168-1.178, indicating that environmental lead in lead mining, sizable coal reserves, and belated phasing-out of leaded gasoline. The Bohemian Kingdom, predecessor of Central Europe had been largely affected by human today's Czech Republic, produced one-third of European activity (smelting) even before the beginning of the Industrial silver at the end of the Middle Ages (7). In the 20th century, Revolution. Five of the sites exhibited a nearly constant the Czech Republic was the third largest producer of soft 206Pb/207Pb ratio (1.175) throughout the 19th century, resembling coal in the world (8). Historical data on mining outputs dating the ªanthropogenic baselineº described in Northern back to the 13th century are preserved in Geofond, one of Europe (1.17). At all sites, the206Pb/207Pb ratio of peat the oldest state-run mining archives in the world. Fortu- decreased at least until 1980; at four sites, a reversal to itously, the centrally planned economy during the Com- more radiogenic values (higher 206Pb/207Pb), typical of easing munist era (1948-1989) involved accurate monitoring of pollution, was observed in the following decade nationwide metal, coal, and gasoline consumption. Therefore, (1980-1990). A time series of annual outputs for 14 the strengths and operation times of individual Pb pollution sources can be reconstructed quantitatively. different mining districts dispersing lead into the environment In addition to historical Pb emission inventories, we used * Corresponding author phone: +420-251816540; fax: +420- Pb isotopes as pollution source indicators. Lead has four 204 251818748; e-mail: [email protected]. stable isotopes, the nonradiogenic isotope Pb, the two ² Department of Geochemistry, Czech Geological Survey. uranogenic isotopes 206Pb and 207Pb, and the thorogenic ³ The Hebrew University. isotope 208Pb. The 206Pb/207Pb abundance ratio has been § Princeton University | generally accepted as the most sensitive to change in Universite Aix-Marseille. environmental studies. The Pb isotope ratios depend on how ⊥ Villanova University. # Geofond of the Czech Republic. long Pb and its parents were together before the Pb was O Department of Quaternary Research, Czech Geological Survey. segregated into the mineral under study. The modern crustal ∇ Charles University. lead is relatively highly radiogenic (206Pb/207Pb g 1.20). The 10.1021/es0200387 CCC: $25.00 2003 American Chemical Society VOL. 37, NO. 3, 2003 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 9 437 Published on Web 12/18/2002 from the depth of 4.6 m below surface was 14C-dated at 10 930 ( 140 years BP. Lead isotope signatures of Central European coal were measured in samples collected at six major power plants (Tisova, Vresova, Uzin, Trmice, Melnik, and Chvaletice) and one city heating plant (Strakonice). Lead isotope signatures of leaded gasoline were measured on 10 samples collected between June 1999 and December 2000 throughout the Czech Republic (Prague, Nove Straseci, Kolesov, Veru- sicky, Karlovy Vary, Unesov, Pacov, Vysocany, Chlumec nad Cidlinou, and Vamberk). Lead isotope ratios of 185 samples of Central European Ag-Pb ores were taken from ref 14. Lead Analysis. The total Pb extraction used to prepare samples for both concentration and isotope measurements was described previously [multiple-step HNO3/H2O2 diges- tion combined with ashing (13)]. Lead concentrations in peat FIGURE 1. Study sites (solid circles). Contours denote annual were determined on a Perkin-Elmer atomic absorption atmospheric lead deposition in the 1990s. Data from the Czech spectrophotometer. The individual 2-cm peat increments Hydrometeorological Institute, Prague. Numbers in parentheses are were 210Pb-dated using an ORTEC 576A alpha spectrometer. cumulative Pb depositions since 1900 AD in grams per square meter. The dates were estimated using the constant rate of supply model (15). Three different instruments were used to 206Pb/207Pb ratio in Pb minerals with no uranium decreases determine the 206Pb/207Pb and 208Pb/207Pb isotope ratios: ICP- with increasing geological age. For example, galena from the MS Perkin-Elmer SCIEX ELAN 6000 (119 measurements on 1.7 billion year old deposits at Broken Hill, Australia, largely peat; continuous solution aspiration), ICP-MS-MC (14 peat used for the production of alkyl lead gasoline additives, is samples), and TIMS (Finnigan MAT 262; coal and gasoline characterized by a relatively low 206Pb/207Pb ratio of 1.04 (9). samples). During the ICP-MS measurements, the NIST-SRM It has been unclear whether car exhausts introduced this 981 standard was frequently analyzed to monitor mass Precambrian lead into the environment of Central Europe fractionation. The measured isotope ratios were corrected when it was separated from the West by the Iron Curtain. It when the standard's ratio differed from the certified value has also been unclear whether lead pollution from ore by more than the relative standard deviation (RSD) of the smelting and coal combustion in Central Europe can be analysis. Prior to analysis, the samples measured with the isotopically distinguished. Because both local Ag-Pb ores ICP-MS-MC and TIMS instruments underwent acid dissolu- and coal are Phanerozoic in age, it has been suggested that tion and preconcentration using anion-exchange columns their Pb isotope signatures coincide and are of little use as (BioRed AG-1-x8 resin). For TIMS, the purified samples were source indicators (10). In this study, we have looked for the loaded on Re filaments with silica gel and phosphoric acid. Australian Precambrian traffic-derived lead in Czech eco- The isotopic ratios measured by the ICP-MS apparatus systems and for Pb isotope differences between local ores typically exhibited RSD values of less than 0.3%, whereas and coal. ratios for the TIMS and ICP-MS-MC instruments were near At a receptor site, a smooth shift in Pb isotope ratios should 0.02%. only rarely accompany constant Pb accumulation rates. It is unlikely that, while one isotopically distinct Pb source retreats Results and Discussion and an isotopically different source builds up, the sum of their emission fluxes remains constant. Yet, such cases have Pb Accumulation in Peat. There was general agreement been reported, usually with the conclusion that ªthere are between the contemporary atmospheric Pb loads and discrepancies between isotopes and fluxesº (10-12). In this cumulative Pb contents in the peat profiles since 1900 AD paper, we have focused on such discrepancies.